Abstract 85: MR Imaging of Crohn's Disease in the Gastrointestinal Tract
AUTHORS:
D. Koh, MBBS, Y. Miao, R.J. Chinn, MBBS, Z. Amin, MD, D. Westaby, MD, J.C. Healy, MD.
ABSTRACT:
PURPOSE: To compare the utility of MR imaging and ultrasound (US) in determining the activity of Crohn disease in the gastrointestinal tract.
METHOD AND MATERIALS: A prospective study involving 27 patients with known Crohn disease. All patients were scored for activity with Crohn disease activity index (CDAI). US and MRI were performed by independent radiologists blinded to the clinical scoring, to determine the absence/presence of active disease. On US, bowel wall thickening, mural stratification and superior mesenteric artery (SMA) flow volume were used to determine activity. Breath-hold MRI was performed using gradient-echo and turbo spin-echo sequences before & after i.v.gadolinium. Bowel wall thickening, mesenteric changes and contrast enhancement were used for activity assessment. Endoscopy ± barium study served as a gold standard for activity assessment.
RESULTS: There were 14 females and 13 males with a mean age of 37 years. There is concordance of disease activity assessment by US & MRI in 25/27 cases. CDAI score ranged from 114 to 677. In active disease, US showed bowel wall thickening (100%), increased SMA flow volume 500mls/min (91%), decreased peristalsis (70%) and preservation of mural stratification (70%). MR showed bowel wall thickening (100%), increased perienteric/ mesenteric vascularity (100%) and wall enhancement (100%). There was a statistical difference in the bowel wall thickness (p=0.004) and the SMA blood flow volume (p=0.03) between patients with active and inactive disease. No correlation was identified between CDAI and MR parameters of wall thickeness, length of involvement and percentage enhancement following contrast. No relationship between CDAI with SMA flow volume was identified. A layered enhancement pattern on MRI was associated with a lower CDAI score (p=0.012, Whitney U), the significance of which is uncertain. 17/27 patients had endoscopy ± barium study. 13 patients had active disease and 4 patients had inactive disease. MRI identified 12/13 patients with active disease and 3/4 patients with inactive disease (sensitivity 92%, specificity 75%). US also identified 12/13 patients with active disease and 3/4 patients with inactive disease (sensitivity 92%, specificity 75%). CDAI scored 11/13 patients with active disease but only 1/4 with inactive disease (sensitivity 84%, specificity 25%).
CONCLUSIONS: US and MRI are sensitive in detecting active Crohn disease and are more specific than clinical scoring. US or MRI can be recommended for disease activity assessment when clinical scoring is equivocal.
